Detergent compositions containing polyhydroxy fatty acid amide and anionic sulfate surfactant are known from International Application WO 92-06162.
Copending U.S. patent application Ser. No. 07/755900, it has been disclosed that the addition of calcium to detergent compositions containing polyhydroxy fatty acid amide and anionic sulfate surfactant can improve the removal of greasy soils while delivering good hand mildness in particular when calcium ions are added to light duty liquid dishwashing compositions containing polyhydroxy fatty acid amide and anionic sulfate surfactant, surprisingly improved greasy soil removal from dishes was found.
It is known however that calcium is difficult to formulate into a stable liquid composition; copending U.S. patent application Ser. No. 07/755900 proposes to use lime soap dispersing agents for this purpose; in published Canadian Patent Application No. 20550481 it has been proposed to use certain calcium chelating agents in order to stabilize calcium, in liquid detergent compositions containing an alkyl ethoxy carboxylate surfactant.
It has now been found that calcium or strontium ion containing liquid or gel detergent compositions, containing nonionic surfactant and anionic sulfate or sulfonate surfactant, can be remarkably stabilized by the use of a carboxylate which forms a water soluble calcium or strontium salt, most especially by the use of malic, maleic or acetic acid.
Said compositions may be formulated and sold as liquids or gels. Alternatively the compositions may be made up by dissolving a concentrated composition (sold as a concentrate for dilution), which may be solid or liquid, into water containing divalent ions to form a composition in accord with the invention.
The present invention therefore provides remarkably stable liquid or gel detergent compositions which exhibit superior greasy oil removal properties.